Cooling device of electronic apparatus

ABSTRACT

A cooling device for an electronic apparatus includes a heat generating element attached within a housing, a heat receiving jacket connectable with the heat generating element, a heat exchanger for exchanging heat between the heat receiving jacket and outside of the electronic apparatus and a liquid driver which supplies a cooling liquid to the heat receiving jacket. A part of pipework connected between the heat receiving jacket, the heat exchanger, and the liquid driver is made of a flexible tube of resin, and an ion exchanger is provided in a portion of the pipework. The cooling liquid has a corrosion inhibitor therein.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 10/426,719, filedOct. 26, 2004, the subject matter of which is incorporated by referenceherein.

BACKGROUND OF THE INVENTION

The present invention relates to a cooling device of an electronicapparatus with using a liquid as a cooling means for heat-generatingparts thereof.

An electronic apparatus, such as a computer, for example, generates heatwhen it operates.

In particular, heat generation of highly integrated semiconductor devicerises up in an amount thereof, in recent years. However, since thesemiconductor device will loose the function as it is, when exceeding acertain temperature, therefore it is necessary to conduct coolingthereon effectively.

As a means for cooling the semiconductor device in the electronicapparatus, those are already known, such as, a natural cooling systemthrough a phenomenon, the heat conduction, a compulsive air coolingsystem by means of a fan, or a liquid cooling system with using a heatpipe therein, for example.

In the natural cooling system, the cooling is achieved by using amaterial having a large heat conductivity within a heat radiation pathreaching from the semiconductor device to an outside of the electronicapparatus.

This method is suitable for use in the semiconductor device having arelatively small amount of heat generation, or for the electronicapparatus, being compact in the size, such as, a personal computer ofnote-type or the like, for example.

In the compulsive air cooling system by means of a fan, etc., theair-blowing device is provided within the electronic apparatus, therebygenerating the convection, compulsively, for cooling the semiconductordevice provided therein.

Since being suitable for use in cooling of the semiconductor, which hasan amount of heat generation up to a certain degree thereof, this methodis widely used, in general, and is also applied into a personal computerwith making the air-blowing device small in the sizes and thin in thethickness thereof.

In the cooling of using the heat pipe therein, the heat of thesemiconductor element is transferred by the function of coolant, whichis enclosed within a pipe.

The conventional technology of using such the heat pipe is described,for example, in Japanese Patent Laying-Open No. Hei 1-84699 (JP-A 84699(1989)) and Japanese Patent Laying-Open No. Hei 2-244748 (JP-A 244748(1990)).

With those conventional technologies, though being extremely high in theeffect of saving electric power since there is used no portion,consuming the electric power therein, however there is a limit an amountof heat, which can be transmitted therewith.

Now, a technology is practiced, conventionally, cooling thesemiconductor device generating heat through circulation of a liquidcoolant thereto; thus, water, by means of a pump, etc., for example.Such the cooling means is applied into a large-scale computer dealing alarge amount of data, for use in a bank and/or a company, etc., forexample.

For this conventional technology, relating to a cooling method by meansof the liquid coolant, the following can be listed up; Japanese PatentLaying-Open No. Hei 5-335454 (JP-A 335454 (1993)), Japanese PatentLaying-Open No. Hei 6-97338 (JP-A 97338 (1993)), and Japanese PatentLaying-Open No. Hei 6-125188 (JP-A 125188 (1994)), for example.

However, those conventional technologies are limited to the large-scalecomputer, in uses thereof.

The reason of this lies in that the apparatus as a whole comes to belarge in the sizes since the liquid cooling system needs a large numberof parts for exclusive use of cooling, such as a pump, a piping system,a heat exchanger(s), etc., and that it is difficult to ascertain areliability for safety, comparing to other methods, due to use of theliquid for the purpose of cooling.

Also, one of the other reasons lies in the fact that the semiconductordevice, having such large heat generation that it needs the liquidcooling, is not used, but only in the large-scaled computer.

As the conventional arts, applying such the liquid-cooling technologyfor the large-scale computer into a small size electronic apparatus(such as, the note-type personal computer), the followings can be listedup, for example, Japanese Patent Laying-Open No. Hei 6-266474 (JP-A266474 (1994)), and Japanese Patent Laying-Open No. Hei 7-142886 (JP-A142886 (1995)).

In such the conventional arts, which are described in the JapanesePatent Laying-Open No. Hei 7-142886 (JP-A 142886 (1995)) and theJapanese Patent Laying-Open No. Hei 6-266474 (JP-A 266474 (1994)), animprovement is made on the reliability, in particular with respect tothe heat conductivity and the liquid leakage, by applying a heatreceiving jacket, a heat radiation tube and a metal heat exchangertherein. However, in those conventional arts, the heat receiving jacketand the heat radiation tube are made of metal, by taking the heatconductivity thereof into the consideration.

On a while, the heat receiving jacket is preferable in a plate-type,from the consideration of the heat conductivity thereof, therefore it isnecessary to form flow passages made up with a minute fin structure inthe heat-receiving jacket of such the plate-type. The minute finstructure of the heat receiving jacket can be manufactured with relativeease.

Accordingly, for such the plate-type heat receiving jacket, aluminum ispreferable to form, from the viewpoints, such as, the heat transferperformance, the cost and the processability thereof, while a copperpipe is preferable for the heat radiation pipe and the heat exchangerfrom the viewpoints, such as, the heat transfer performance, the costand the processability thereof.

However, when adopting a combination of the heat receiving jacket madeof aluminum, the heat radiation pipe and the heat exchanger, both madeof copper, being preferable from the viewpoints, such as, the heattransfer performance, the cost and the processability, then there is aproblem that the localized corrosion (or pitting corrosion, crevicecorrosion) of the aluminum is accelerated remarkably, due to copper iondissolved from the copper.

Also, from a tube made of a polymeric material group, which is adoptedto be a connector tube, corrosive ion is dissolved, including halogenion therein, for example; therefore, the localized corrosion is furtheraccelerated, remarkably.

BRIEF SUMMARY OF THE INVENTION

An object, according to the present invention, is to provide anelectronic apparatus, with which an improvement can be obtained onreliability, in particular when being mounted with a cooling devicecombining the copper and the aluminum.

For accomplishing the object mentioned above, according to the presentinvention, firstly, there is provided a cooling device for an electronicapparatus, comprising: a heat generating element attached within ahousing; a heat receiving jacket, being connected with said heatgenerating element; a first heat exchanger for exchanging heat betweenan outside; and a liquid driving means for supplying a liquid to saidheat receiving jacket, wherein a part of pipework connecting betweensaid heat receiving means, said first heat exchanger, and said liquiddriving means is made from a flexible tube of resin, and furthercomprising, a second heat exchanger and an ion exchanger, which areprovided in a part of said pipework.

Also, according to the present invention, in the cooling device for anelectronic apparatus, as described in the above, wherein said ionexchanger absorbs therein a corrosion inhibitor in advance, and saidcooling liquid is added with a corrosion inhibitor therein.

And, also according to the present invention, in the cooling device foran electronic apparatus, as described in the above, wherein said heatreceiving jacket is made of an aluminum group material, said second heatexchanger is made of a copper group material, said liquid medium is ananti-freezing liquid or a pure water, and into said cooling liquid isadded a corrosion inhibitor for the copper group material.

Further, according to the present invention, for also achieving theobject mentioned above, there is also provided a cooling device for anelectronic apparatus, comprising: a heat generating element attachedwithin a first housing; a heat receiving jacket, being connected withsaid heat generating element, and being attached within said firsthousing; a second housing being rotatably supported on said firsthousing; a first heat exchanger attached within said second housing, forexchanging heat between an outside; and a liquid driving means forsupplying a cooling liquid to said heat receiving jacket, wherein aportion of a pipe for connecting between said heat receiving means, saidfirst heat exchanger, and said liquid driving means is made of aflexible tube made of a resin, and further wherein, a second heatexchanger and an ion exchanger are provided in a part of said pipe, saidsecond housing is received within said second housing, and said ionexchanger is received within said second housing.

Also, according to the present invention, in the cooling device for anelectronic apparatus, as described in the above, wherein said secondheat exchanger is cooled by means of a fan.

And also, according to the present invention, in the cooling device foran electronic apparatus, as described in the above, wherein said ionexchanger absorbs therein a corrosion inhibitor in advance, and saidcooling liquid is added with a corrosion inhibitor therein.

Furthermore, according to the present invention, in the cooling devicefor an electronic apparatus, as described in the above, wherein adisplay device made from a liquid crystal panel is provided in saidsecond housing, and said ion exchanger is provided on a reverse sidesurface of said liquid crystal panel.

BRIEF DESCRIPTION OF THE DRAWINGS

Those and other objects, features and advantages of the presentinvention will become more readily apparent from the following detaileddescription when taken in conjunction with the accompanying drawingswherein:

FIG. 1 is a perspective view of a first embodiment, according to thepresent invention;

FIG. 2 is a block diagram of the first embodiment, according to thepresent invention;

FIG. 3 is a graph for showing a relationship between the local corrosiongenerating potential of aluminum and the halogen ion concentration;

FIG. 4 is a graph for showing a relationship between an amount ofcorrosion of copper and the benzotriazole concentration within a coolingliquid;

FIG. 5 is a graph for showing a relationship between the benzotriazoleconcentration within an ion exchange resin and the benzotriazoleconcentration within the coolant; and

FIG. 6 is a graph for showing a relationship between an ion exchangingcapacity and the benzotriazole concentration within the ion exchangeresin.

DETAILED DESCRIPTION OF THE INVENTION

In recent years, an increase jumps up high in heat generation of thesemiconductor devices, accompanying with a large-capacity and alarge-scale of electronic apparatuses, such as, a personal computer, aserver, a workstation, as well as, a plasma display (PDP), a television,a liquid crystal display, etc.

Since it is insufficient to cool down the semiconductor devices, beinghigh in the heat generation in such the manner, in the cooling capacitythereof, by means of the cooling means, such as, the heat conduction,the air-cooling, the heat pipe, etc., studying is made on mounting of acooling device onto those electronic apparatuses, which circulates thecooling liquid mentioned above therein.

In particular, for application thereof into the electronic apparatus,being required to be extremely small in the sizes and thin in thethickness, such as, the personal computer of note-type, furthertechnical innovation is needed. Accordingly, the inventors of thepresent invention try to bring a housing of the electronic apparatus tobe made of metal, being satisfactory in the heat conductivity, etc.,thereby enabling mounting of the liquid cooling system onto such thenote-type electronic apparatus.

Then, when mounting the liquid cooling system onto the note-typeelectronic apparatus at present state (for example, A4 size, class 30W),it is possible to obtain a satisfactory effect on heat radiationthereof. However, there is very high possibility in future, that anelectronic apparatus will be developed, which exceeds 30W in the class,therefore it will be necessary to use the liquid cooling system togetherwith the fan cooling system in common (thus, so-called “hybrid”). Insuch the case, a second heat exchanger for use in heat radiation will benecessary other than the heat radiation pipe.

In general, since the heat exchanger uses a copper pipe therein, it isknown that the following harmful effect will occur when the heatreceiving portion of aluminum is used together with the heat exchangerof copper in common.

Namely, for the purpose of adopting the liquid cooling system, which hasbeen used in the conventional large-scale computer, into the electronicapparatus, to be extremely small in the sizes and thin in the thickness,it is a necessary condition that the liquid cooling system itself beextremely small in the sizes and thin in the thickness. For this reason,in the liquid cooling system for use in such the small-size andthin-thickness electronic apparatus, an amount of the cooling liquid orcoolant comes down to be remarkably small, i.e., {fraction (1/10,000)},comparing to that in the large scale computer, so that the liquidquality can be degraded remarkably if dissolution occurs on corrosiveion even in a small amount thereof. And, if such the liquid degraded inthe quality thereof circulates within the heat receiving jacket, theheat radiation pipe and/or the heat exchanger, the corrosion isaccelerated at the metal portion thereof, and there is provability thatthe liquid leakage occurs from the corroded portion, thereby causingelectric accident. Accordingly, it is necessary to take anticorrosivemeasure on the members in contact with the liquid, in particular, thematerials thereof.

Then, according to the present invention, as a result of various studiesmade about the anticorrosive measures, the following embodiments can beobtained.

Hereinafter, one embodiment according to the present invention will beexplained, by referring to FIGS. 1 and 2.

FIG. 1 is a perspective view of an electronic apparatus according to thepresent invention.

FIG. 2 is a diagram of a cooling system mounted within the electronicapparatus.

In FIGS. 1 and 2, the electronic apparatus comprises a main-body case orhousing 1 and a display case or housing 2, which has a display built upwith a liquid crystal panel. This display case 2 is connected to themain-body case 1 through a hinge (not shown in the figures), beingfreely rotatable.

In the main-body case 1 are provided a key board 3, a printed circuitboard 4 mounting plural numbers of electronic devices thereon, a harddisc drive 5, an external memory device(s) (such as, a floppy disc driveand/or a CD drive, etc.) 6, a battery 13, and so on. On the printedcircuit board 4 is mounted, in particular, an electronic device having alarge amount of heat generation, such as, a central processing unit 7(hereinafter, being described by “CPU”), for example. On the CPU 7 isattached a heat receiving jacket 8. The CPU 7 and the heat receivingjacket 8 are connected with each other through a soft heat-conductivematerial (for example, a mixture of heat-conductive filler, such as,aluminum oxide, into silicon rubber).

On a rear surface of the display case 2 (i.e., in an inside of thecase), a heat radiation plate 10 made of metal is provide, on which isconnected a heat radiation pipe 9. In an upper portion of the rearsurface of the display case 2 is provided a tank 14, which is connectedto the heat radiation pipe 9. The tank 14 has such a capacity that itcan keep an amount of cooling liquid necessary for obtaining coolingwithin the circulating passage even if the coolant comes down due to thepermeation of liquid from the structural materials and the sealingmaterials thereof.

Also, a pump 11, as a liquid driving means, and a heat exchanger 15, forconducting heat exchange between an outside, are provide within themain-body case 1. Though the heat exchanger 15 achieves heat exchangebetween the outside, in the similar manner to that of the heat radiationpipe 9, however since it is possible to improve the performance of heatradiation remarkably, by using an air cooling fan 17 in common,therefore it is applicable into the semiconductor device of high heatgeneration.

An ion exchanger 16 is suitably located at a position within the displaycase, where the temperature is at the lowest therein. In this case, itcan be considered that a portion be most suitable, in an exit portion ofthe tank 14, through which the liquid cooled down by means of the heatradiation pile 9 flows out, and also in the vicinity of the liquidcrystal panel. This is because; the heat generation of the liquidcrystal panel is very low far from that of the heat radiation pipe 9.The heat receiving jacket 8, the heat radiation pipe 9, the ionexchanger 16 and the pump 11 are connected to through a connector tube12, and the cooling liquid enclosed in the cooling system is circulatedby means of a pump 11. This connector tuber 12 is made up from aflexible tube, such as of isobutylene-isoprene rubber, etc., being ableto reduce the liquid from permeation therethrough. Further, the reasonof using such the tube of isobutylene-isoprene rubber lies, of coursefor reducing the liquid from permeation, in that it is rather easy towind round the connector tube in the narrow space within the main-bodycase 1, with the flexibility thereof.

Also, in the case of the note-type personal computer, which is alwaysopened and closed, at least the hinge portion thereof must be connectedthrough a pipe or conduit having the flexibility; therefore thenecessary condition is that it is the flexible tube.

Furthermore, the coolant enclosed within this cooling system is purewater, for example, or an anti-freezing liquid or solution, inparticular when it is exposed under the environment at the freezingtemperature or lower than that.

It is preferable to provide the ion exchanger 16 in a front stage of thepump, where the temperature is lowest within the system, since ionexchanger resin within the ion exchanger 16 is easily degraded throughoxidation under the high temperature.

However, the ion exchanger 16 may be unified or integrated with the tank10 or the pump 11 in one body. Into the ion exchanger resin is absorbedcorrosion inhibitor (for example, benzotriazole, tolyltriazole) for thematerial of a copper group, in advance, and further, the corrosioninhibitor for the material of copper group is absorbed into the coolingliquid. Into the ion exchanger resin, the corrosion inhibitor isabsorbed in equilibrium. If absorbing the corrosion inhibitor only intothe cooling liquid at concentration being higher than a preset set valuewhile no corrosion inhibitor into the ion exchanger resin, a portion ofthe corrosion inhibitor added into the cooling liquid is absorbed intothe ion exchange resin, therefore it comes to be under the same liquidquality where the corrosion inhibitor is added into the cooling liquidat the preset set concentration thereof. On the contrary, it is alsopossible to obtain the same liquid quality by absorbing the corrosioninhibitor only into the ion exchanger resin, at the concentration beinghigher than the preset set value, while no corrosion inhibitor is addedinto the cooling liquid.

For the high heat generating CPU 7, the heat receiving jacket and heatexchanger are required to have high cooling performances. Forming fineor minute fin structure enables the heat receiving jacket to enlarge theheat conductive area thereof, thereby improving the coolingperformances.

For the purpose of such the fin structure, the die-casting is preferablefrom viewpoints of the performances, the cost and the productivity, andaluminum is used to be the material thereof. On the other hand, for theheat radiation pipe and the heat exchanger, the heat conductiveperformances can be improved by attaching the heat radiation fin (i.e.,of aluminum) on an outside of the heat conductive pipe thereof.Connection between the heat conductive pipe and the heat radiation finis preferably achieved through pipe expansion (by expanding the pipe)from viewpoints of the const and the productivity thereof, and copper isused to be the material thereof. However, stainless steel, though beingsuperior in the anticorrosive property, is inferior in the heatconductivity, comparing to copper, and further is high in rigidity,therefore being difficult to expand the pipe made thereof. Accordingly,it can be said that aluminum and copper are inevitable constituentmaterials, i.e., the heat receiving jacket made of aluminum, and theheat radiation pipe and the heat exchanger made of copper.

In case where aluminum and copper coexist in this manner, the copper iondissolved from the copper accelerates the localized corrosion ofaluminum, remarkably.

FIG. 3 shows a relationship between the localized corrosion generatingpotential of aluminum and the halogen ion concentration (such as,chlorine ion, bromine ion, etc.) in the coolant.

In FIG. 3, the localized corrosion occurs on aluminum when the corrosionpotential (i.e., the potential when aluminum is dipped into the coolant)is more noble (i.e., on a side of plus potential) than the localizedcorrosion generating potential. In a system, in which the copper ioncoexists in the coolant, since the copper ion dioxides on the surface ofaluminum, the potential of aluminum is shifted to the noble side (i.e.,on the side of plus potential), therefore the localized corrosion occurson aluminum, easily. In particular, for achieving the small sizing ofthe cooling system, or in a case where the connector tube is adopted,being made of a material of a polymeric material group, for obtainingeasy assembling, the halogen ion (such as, chlorine ion, bromine ion,etc.) is dissolved from the connector tube. As is shown in FIG. 3, thelocalized corrosion potential of aluminum is shifted to a base side (ona side of minus potential) as the halogen ion within the coolant comesto be high in the concentration thereof. The dissolution of the halogenion accelerates the localized corrosion of aluminum, remarkably.

In the high heat generation semiconductor device, wherein it isessential to utilize the heat receiving jacket made of aluminum, and theheat radiation pipe and the heat exchanger, both being made of copper,it is effective to remove the halogen ion from the connector pipe madeof the organic material group, as well as to reduce the dissolution ofthe copper ion from the heat radiation pipe and the heat exchanger madeof copper, so as to inhibit the localized corrosion on the heatreceiving jacket of aluminum.

Conventionally, suppression or control on the dissolution of the copperion is achieved by adding the corrosion inhibitor both aluminum andcopper, and further, the localized corrosion of aluminum by thecorrosion inhibitor for aluminum. However, in a case where the coolingsystem is operated for a long term under the condition of freemaintenance, there is provability that the corrosion resistance isreduced down due to exhaustion of the corrosion inhibitor. Then, acooling system is required, which can maintain the corrosion resistancefor a long time.

In the cooling system, according to the present invention, the ionexchanger is provided, absorbing the corrosion inhibitor for thematerial of the copper group into the icon exchanger resin thereof;thus, it has a means for capturing the halogen ion, and reducing thedissolution of the copper ion into the coolant, by paying an attentionto the copper ion and the halogen ion, being a main factor of causingthe localized corrosion on aluminum.

From the facts that there is no definitive one as to be the corrosioninhibitor for aluminum, and that a great effect can be acknowledged onthe corrosion inhibitor for copper, it is characterized that thelocalized corrosion can be inhibited effectively for a long time withoutusing the corrosion inhibitor for aluminum. Also, since the copper ion,which is dissolved from the heat radiation pipe and the heat exchangermade of copper, is captured on the ion exchanger, therefore thecorrosion resistance of the heat receiving jacket of aluminum can beimproved furthermore. As to be the corrosion inhibitor for copper areeffective the derivatives of benzotriazole, such as, benzotriazole,tolyltriazole, etc., for example.

FIG. 4 shows a relationship between an amount of corrosion on copper andthe concentration of benzotriazole within the cooling liquid.

From FIG. 4, it can be seen that the corrosion on copper can be reduceddown to be {fraction (1/50)} if adding benzotriazole to be 10 ppm ormore therein, while suppressing the dissolution of the copper ion to be{fraction (1/50)}. Hereinafter, description will be made on a case wherethe benzotriazole is added to be 50 ppm, expecting the safety therein.

FIG. 5 shows a relationship between the concentration of benzotriazolewithin the ion exchanger resin and the concentration of benzotriazolewithin the cooling liquid.

In FIG. 5, since being ionized a little bit to cause hydrogen ion, thebenzotriazole shows a weak acidity; therefore it is mainly absorbed ontoan anion exchange resin. In the vicinity of 50 ppm of the benzotriazoleconcentration, since the absorption (i.e., reversible absorption) ontothe anion exchange resin increases abruptly, the benzotriazole in theion exchange resin is electrolytic dissociated therefrom, in spite ofconsumption of the benzotriazole within the cooling liquid, therebymaintaining the concentration of benzotriazole within the cooling liquidto be constant.

FIG. 6 shows a relationship between an ion-exchanging capacity (i.e., acapacity of absorbing ion therein) and the concentration ofbenzotriazole within the ion exchange resin.

In FIG. 6, when benzotriazole exists in the cooling liquid at the presetset concentration, such as, 50 ppm, the concentration of benzotriazolewithin the ion exchanger resin is 80 mg/mg resin (the concentration ofbenzotriazole per 1 mg of the ion exchange resin) by an anion ionexchange resin, while 10 mg/mg resin by an cation ion exchange resin,from FIG. 5, for example. When the benzotriazole mentioned above isabsorbed into the ion exchange resin, the exchanging capacity thereof isreduced by 60% for the anion exchange resin, while by 10% for the cationexchange resin, from FIG. 6, for example. Thus, it is possible tocapture halogen ion to be the anion, fully or satisfactorily, even whenletting the benzotriazole absorbed therein. It is also possible to makea capacity ratio of the ion exchange resin large, in advance, comparingto that of the cation exchanger resin, so as to capture the copper ion,fully or satisfactorily.

From the above, with provision of the ion exchange resin enclosed withinthe ion exchanger, in an amount so that it can absorb the halogen iondissolved from the connector tube made of the polymeric material group,and also the copper ion dissolved from the heat radiation pipe and theheat exchanger made of copper, fully and satisfactorily, and furtherbeing sufficient for absorbing the benzotriazole, so as to maintain theconcentration of the benzotriazole within the cooling liquid at a presetvalue, therefore it is possible to ascertain the corrosion resistance inthe cooling system for a long term.

As was fully mentioned in the above, according to the present invention,there is obtained the cooling device for an electronic apparatus,preventing from liquid leakage due to generation of the localizedcorrosion on the heat receiving jacket, through dissolution of ion ofheavy metal, in particular, the copper ion, and dissolution of corrosiveion from the tube made of the polymeric material group.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential feature or characteristicsthereof. The present embodiment(s) is/are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims rather than by theforgoing description and range of equivalency of the claims aretherefore to be embraced therein.

1. A cooling device for an electronic apparatus comprising: a heatgenerating element attached within a housing; a heat receiving jacketconnectable with the heat generating element; a heat exchanger forexchanging heat between the heat receiving jacket and outside of theelectronic apparatus; and a liquid driver which supplies a coolingliquid to the heat receiving jacket, wherein a part of pipeworkconnected between the heat receiving jacket, the heat exchanger, and theliquid driver is made of a flexible tube of resin, and furthercomprising: an ion exchanger provided in a portion of the pipework;wherein the cooling liquid has a corrosion inhibitor therein.
 2. Thecooling device, as defined in the claim 1, wherein the ion exchanger isprovided in the portion of the pipework where temperature is lowest inthe electronic apparatus.
 3. The cooling device, as defined in the claim1, wherein the ion exchanger is provided in a portion of the pipeworkbetween the heat exchanger and the heat receiving jacket.
 4. The coolingdevice, as defined in the claim 1 wherein the ion exchanger is providedin a front stage of a pump of the liquid driver.
 5. The cooling device,as defined in the claim 3, wherein the ion exchanger is provided in afront stage of a pump of the liquid driver.
 6. A cooling device for anelectronic apparatus comprising: a heat generating element attachedwithin a housing; a heat receiving jacket connectable with theheat-generating element; a heat exchanger for exchanging heat betweenthe heat receiving jacket and outside of the electronic apparatus; and aliquid driver which supplies a cooling liquid to the heat receivingjacket; wherein a part of pipework connected between the heat receivingjacket, the heat exchanger, and the liquid driver is made of a flexibletube of resin, and further comprising: an ion exchanger, which isprovided in a portion of the pipework; wherein at least the heatreceiving jacket and the heat exchanger are made of different materials,each of the different materials being selected from aluminum groupmaterials and copper group materials, wherein the cooling liquid is oneof an anti-freeze liquid and pure water, and wherein the cooling liquidhas a corrosion inhibitor for the copper group materials.
 7. The coolingdevice, as defined in the claim 6, wherein the ion exchanger is providedin the portion of the pipework where temperature is lowest in theelectronic apparatus.
 8. The cooling device, as defined in the claim 6,wherein the ion exchanger is provided in the portion of the pipeworkbetween the heat exchanger and the heat receiving jacket.
 9. The coolingdevice, as defined in the claim 6, wherein said ion exchanger isprovided in a front stage of a pump of the liquid driver.
 10. Thecooling device, as defined in the claim 8, wherein the ion exchanger isprovided in a front stage of a pump of the liquid driver.
 11. A coolingdevice for an electronic apparatus comprising: a heat generating elementattached within a first housing; a heat receiving jacket connectablewith the heat generating element; a second housing rotatably supportedon the first housing; a heat exchanger attached within the first housingfor exchanging heat between the heat receiving jacket and outside of theelectronic apparatus; and a liquid driver which supplies cooling liquidto the heat receiving jacket; wherein a part of a pipe connected betweenthe heat receiving jacket, the heat exchanger, and the liquid driver ismade of a flexible tube of resin, and further comprising: an ionexchanger provided in a portion of the pipe which is received within thesecond housing; wherein the cooling liquid has a corrosion inhibitortherein.
 12. The cooling device, as defined in the claim 11, wherein theion exchanger is provided in the portion of the pipe where temperatureis lowest in the electronic apparatus.
 13. The cooling device, asdefined in the claim 11, wherein the ion exchanger is provided in theportion of the pipe between the heat exchanger and the heat receivingjacket.
 14. The cooling device, as defined in the claim 11, wherein theion exchanger is provided in a front stage of a pump of the liquiddriver.
 15. The cooling device, as defined in the claim 13, wherein theion exchanger is provided in a front stage of a pump of the liquiddriver.